Optimal Design of Small Power DC PM Commutator Motors, Part I: Analytic Model

An analytical model suitable for the design optimization of permanent magnet DC motors is presented. The model, which combines electric, magnetic and physical aspects, takes into account the brush drop characteristics, tri-dimensional aspect, and the magnetic saturation. An original method for modeling commutation effects on no-load electromotive force and equivalent armature resistance computations is used. Analytical approach is able to predict motors characteristics with weak errors. Model forecasts are consistent with results obtained by finite elements analysis (for magnetic circuit) as well as with experimental results (for electric circuit).